Re ECF Project: ECF 2015-85

Project Title: Impacts of alien herpetofauna on the local ecosystem in Hong Kong

Applicant: Dr SUNG Yik Hei, Department of Biology, Hong Kong Baptist University

Total Approved Grant: $367,480

Duration: 1/3/2016 to 31/12/2017

Project Status/Remarks: Completed

This project aims to assess the ecological impacts of alien herpetofauna species on the local ecosystem so as to formulate proper measures to control alien/invasive species in Hong Kong. Its objectives are:

1. To investigate the population occupancy and population density of Green House Frogs in Hong Kong, particularly in the native distribution of Romer's Tree Frogs including Lantau Island, Lamma Island and Po Toi Island;
2. To identify morphological characters to distinguish native and introduced Chinese Bullfrogs by genetic analysis;
3. To investigate the population density, population structure of Chinese Water Dragons; and
4. To investigate the diet of Green House Frogs, released Chinese Bullfrogs and Chinese Water Dragons so as to evaluate their impacts on other native animals.

The information yield in this study will facilitate formulation of proper measures to control alien herpetofauna.

Summary of the Findings/Outcomes:
Invasive species is one of the major threats to biodiversity that has led to a number of extinction events globally. Studies on alien herpetofauna, i.e. amphibians and reptiles, have been lacking despite a number of different alien herpetofauna species have been introduced. This project focuses to study the ecological impacts of three alien species—Green House Frogs, released Chinese Bullfrogs and Chinese Water Dragons. The research team found that Green House Frogs may pose a threat to the endemic Romer’s Tree Frogs, as they occur together in multiple sites and potential have similar diets. They identified sites where Chinese bullfrogs released in mercy release persist and found that they consume native animals. Using genetic and morphological analyses, the research team identified morphological characteristics that will be useful in distinguishing released and native Chinese Bullfrogs so as to prevent accidental removal of native individuals during future eradication. Chinese Water Dragons occur at high density along the study streams and consume a diet consisting of diverse invertebrates. This study provides important baseline information on the source of diet of Chinese Water Dragons. Further studies are needed to determine the impacts of Chinese Water Dragons on the local ecosystem. Findings of the project were disseminated through presentation in four public seminars in Hong Kong. Two manuscripts were submitted.